Activated and shorter Laser-Scribed graphene Electrodes: Excellent electrochemical signal amplification for detecting biomarkers

Laser-scribed graphene electrodes (LSGEs) are emerging as powerful transducers in electroanalysis. Surface structure and electrode geometry are the two key properties that heavily influence the characteristics of the resulting biosensors. In this work, we have investigated the sensing abilities of the LSGEs at various electrochemical activation procedures and electrode geometry conditions. We found that electrochemically activated LSGEs with shorter electrode connection lengths outperform corresponding non-activated LSGEs with longer electrode connection lengths. The effects of different pH conditions, supporting electrolytes, polarization potentials, and activation time were studied. X-ray photoelectron spectroscopy, Raman spectroscopy, and voltammetry techniques were used to examine the in-situ formation of porosity, introduction of surface oxygen functionalities, role of defect densities, and electrochemically accessible area. Dopamine is used as a model to study the sensing capabilities of the electrodes. Activated LSGE offered a 5.4-fold enhanced detection limit for dopamine compared to longer and non-activated LSGE. Practicality of the method is validated in human serum and urine samples. In addition, the sensor was demonstrated in monitoring in-situ dopamine released by neuroblastoma SH-SY5Y cells. Additionally, the enhanced sensing performance of the activated LSGEs are also tested by sensing uric acid and paracetamol. Electrochemically activated, shorter LSGEs hold great potential in various electrochemical applications.